Burglar alarm



J. NOWAKOWSKI Nov. 17 1925 1,562,039

BURGLAR ALARM Filed Oct. 9. 1923 Patented Nov. 17, 1925.

UNITED STATES PATENF QFFE.

JOHN NOWAKOWSKI, OF MILWAUKEE, VISCONSIN, ASSIGNQR OF ONE-.HALE TG STEV LUKASZEWICZ, OF MILVVUKEE, WISCNSIN.

BURGLAR ALARM.

Application 'filed October 9, 1922v Seria] No. 667,464.

To all 107mm z't may com-era:

Be it known that I, JOHN NowAKowsKr, a citizen of the United States, and resident of Milwaukee, in the county of Milwaukee and State of IVisconsin, have invented certain new and useful Improvements in Burglar Alarms; and I do hereby declare that the following is a full, clear, and exact description thereof.

This invention pert-ains to burglar alarms and more particularly to a device adapted to operate a signal upon the insertion of a key or implement into a doorlock.

The primary object of the invention resides in the provision of a device of the above character adapted to be inserted into the lock of a door, which will close an electric circuit and operate either a visible o-r audible signal, should the device be engaged by a tool or any form of implement inserted into the lock.

Vith the above and other objects in view, which will appear as the description proceeds, the invention resides in the novel construction, combination and arrangement of parts, substantially as hereinafter described and more particula-rly defined by the appended claim, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made. as come within the scope of the claim.

In the accompanying drawing is illustrated one complete example of the physical embodiment of the present invention constructed according to the best mode so far devised for the practical application of the principles thereof.

In the drawingsz- Figure 1 is an elevational view partly broken away and in section tol more clearly illustrate. the structural details, and

Figure 2 is a transverse sectional view taken on the line 2-2 of Figure 1.

Referring more particularly to the accon'ipa'nying drawings, the present invention is designed in the form of a key comprising a hollow shank 1 provided at one end with a lock operating projection 2 and at the other end with an enlarged ho-llo-w head 3 which is split for the purpose of reducing the cost of manufacture and allowing removal of the mechanism carried within the head. The cover' 4 is secured to that portion of the head carried by the key, by means of Screws 5.

Slidably mounted within the shank 1 and normally projectiing slightly therefrom is a plung'er 6 provided with a head disposed within the casing 8 and adapted to engage a contact member 7 sccured to the insulz'iting block 8 mounted within the casing. A second contact 9 is positioned adjacent the contact 7 and is also insulated from the c'asing by the block 8.

Connected with the contacts 7 and 9 is an electric circuit 11 illustrated iii diagrammatic form in connection with Figure- 1. This circuit is provided with the cnstoinary battery, or other source of electrical supply B, and an audible signal, such as the bell O. In addition to the foregoing the circuit may be provided, when so desired, with a visible sign al, in the form of an incandescent light, D.

From the foregoing description taken in connection with the drawing it will be obvious that when the shank l is positioned within the lock of a door, any tool or implement inserted from the' opposite side, for the. purpos-e of turning the key prior to forcing it out of the lock, will engage the projectiing end of the plunger 6 causing the same to move longitudinally within the shank whereupon the contact 7 eng'ages the contact 9, closing the circuit 11 and actuating the desired sigina-ls. It will also be observed that the present invention, being constructed in the form of a key, will in no way interfere with the operation of the door from that side which carries the device. Consequently its removal, in order to lock or nnlock the door, is eliminated.

I claim:-

A device of the class described comprising a door key having a hollow shank, a lock Operating projection at one end of said shank, an Oval shaped handle at the other end of said shank and having an ope'ning concentr-ic with the opening in said shank, said handle being formed of two cup-shaped parts, the inner of said parts being rigid with said shank, the outer of said parts being detachable and provided with a centrally located opening, screws securing the outer part tol said i'nner part, a plunger slidably mounted within said shank and having an end projecting from the outer endof said shank and having an enlarged head at its rear end positioned within the inner part of said handle, an insulating block secured within Jche inneil part of Said handle and having an opening surrounding the enlai'ged head of said shank, a contact spring carried by said block and beai'ing against the end of Said head, a second contactspring secured to said bloci; and 10- cated behind said first vifnentione-d spring, and conductors connected to said Spring and -passing through the aperture in the outei' poi'tion of said handle. 10 111 testiniony that ciaim the foi'egoing I have i'ieifeunt-o set my hand ilW-aukee,

in the county of 'Yiilwaui'ee and State of 'Visconsin.

JOHN OVAKOXVSKI. 

